Just bought the materials for a 5x10 frame :
30 feet of 2x2x.095 main rails and front and back cross members
10 feet 2x2x.125 angle for the 2 inner cross members
5 feet of 2x3x .125 for the tongue
2" ball coupler
total for frame materials and coupler 125.00(aprox)
dexter #9 torsion axle quote 197.95
trailer wheels with tires 5x13 85.00
steel fenders round with 2" rounded lip 30.00
2 hrs fab shop welding time 100.00
total 538.95
I have the equipment and skills to do my own fab and welding but my wheels and tires are costing as much as I could build this trailer for.
I f you use a harbor freight trailer you are starting with a handicap as you are stuck with the size and light weight frame materials.... if you buy a "farm supply " trailer you will have the same problem as to starting size and the cost is all out of reason.. find a "hobby friend " and trade skills tfor the fab and welding ( I could use the skills of a cabinet maker for my galley)
The difficult we do now... the impossible takes a little longer